When scheduling was converted from days to hours, one conversion wasn't
addressed.

There are two factors that apply:

Time per estimate (how many scheduling units are in each unit of

estimate (and work)

Hours per day (how much work gets done each day)

The former affects the size of the task, the latter affects the
duration. Both conversions were muddled up in _workHours() because we
used to convert estimate to days and wrongly concluced we then needed to
scale by hours per day to get work.

A failed case was an hour as a unit of estimate and a 6-hour work day
(or a day when only 6 hours of work get done). With an estimate of 8,
days per estimate of .125, and hours per day of 6, this gave:

hours = (8 * .125) * 6

Which converted the task for 8 hours to 6!

We first need to convert estimate to the unit of scheduling (hours) so
days_per_estimate becomes hours_per_estimate. Computing work hours is
then just (estimate * hours per estimate).